PROJECT SUMMARY Adolescents and young adults (AYA) living with HIV in South Africa are at high-risk for HIV treatment failure and death. Only 10% are virally suppressed, despite widespread treatment availability. There is a dearth of evidence regarding the effectiveness of interventions focused on improving antiretroviral therapy (ART) initiation and retention in this key population. Formative research by Katz (PI) et al., has shown that South Africans newly diagnosed with HIV may not initiate ART due to social costs associated with being ?sick.? For these individuals, social integration and connectivity may promote effective coping strategies. Bekker (Site-PI) et al., developed a model of care (?The Hlanganani Program?) that utilizes social integration to engage AYA, newly diagnosed with HIV in clinic facilities, in a dynamic, three-session cognitive behavioral support group facilitated by lay health counselors (LHCs). The intervention shows promising early results (100% linkage to an initial HIV clinic visit among a sub-sample tested vs. 58% in historical controls, p<.001). Despite this early success, potential implementation was limited by a lack of a concurrent control arm. In the proposed R34, we will adapt this socio-behavioral intervention through an iterative approach, to address individual, social, and structural barriers to treatment initiation and viral suppression for South Africans, ages 18-24, newly diagnosed with HIV. The proposed intervention, titled Standing Tall, is guided by Social Action Theory and has three interrelated components: (1) a three-session group intervention adapted from Hlanganani, delivered weekly by LHCs, focused on treatment uptake, adherence, and health maintenance (addressing individual factors); (2) six months of ongoing treatment and social support (addressing social factors); and (3) provision of immediate ART and refills in the context of an ART Initiation Club (addressing structural factors). We will inform the design of our intervention by performing semi-structured qualitative interviews with 20 AYA newly diagnosed with HIV, with attention to gender-specific needs in this population, and 10 healthcare providers (Aim 1). We will then test components of the intervention with 10 AYA newly diagnosed with HIV using an iterative phased approach (Aim 2). Finally, we will leverage established community-based testing platforms created at the Desmond Tutu HIV Foundation which provide rapid HIV-testing, to conduct a pilot randomized controlled trial of our intervention (Aim 3). One-hundred ART-nave, AYA newly diagnosed with HIV will be randomly assigned to one of two study arms: 1) Standing Tall or; 2) treatment as usual (immediate referral for ART at local clinics). Behavioral and biological data will be collected to assess the impact of Standing Tall on ART initiation within three months of testing, viral load suppression and engagement in care at six months of ART initiation, and psychosocial mediators of ART initiation across the two arms of the study. To assess feasibility and acceptability of the intervention, we will use a mixed-methods process evaluation (qualitative, quantitative, and observational methods) of the intervention components and their implementation.